Pros: A tiny pair of wireless add-ons that turn an iPod nano and a pair of shoes into a miniature personal running or power walking tracker, adding easy-to-use time, distance, and calorie-based workout options to the nano’s existing menus. Impressive male or female voice feedback automatically or manually updates you on your progress towards goals without requiring you to look at the screen, or interrupting your music; on-iPod and on-computer data viewing options able you to track your performance over time. Spectacular Nikeplus.com web design makes comparative data viewing fun; integration with iTunes makes it easy. Reliable, generally accurate accelerometer hardware, backed by a wide variety of good shoe designs.

Cons: Accessory is physically compatible only with specific pairs of one company’s sneakers, unless user manually modifies or augments other models. Entire system needs to be replaced when sensor’s battery dies, partially forgivable only because of low price. Doesn’t - as of date of review - work with iPods other than the nano. Other than shoes, company’s supporting Nike+ apparel needs a little iPod integration work.

Two months after its unexpected joint announcement by Apple Computer and sport apparel maker Nike, the Nike + iPod Sport Kit ($29) is now available in stores, along with a variety of compatible Nike+ ("Nike Plus") shoes and clothes. Designed to work only with the iPod nano - at least for now - the Sport Kit consists of a small red and white wireless 2.4 GHz sensor/transmitter, and an all-white iPod nano receiver, which together track and store data on a runner's or walker's performance for later synchronization with iTunes. In order for the Kit to work as intended by Apple and Nike, the sensor must be inserted into a pocket within any Nike+-branded shoe, a requirement that can be worked around by a user with non-Nike+ footwear, but is more easily satisfied with them.

A summary of the Nike + iPod Sport Kit should begin by acknowledging that it's one of the companies' most impressive accomplishments to date: a nearly seamless fusion of hardware, software, and footwear that will instantly appeal to any runner or power walker who likes Nike products, and even some who don't. We consider the aggregate development effort of these components to be outstanding, expanding the iPod nano's capabilities in a creative new way, providing a beautiful on-computer interface for tracking your performance, and offering it all at an appealing price. The only big issues are three: first, once the sensor's internal battery dies, you need to buy another Kit - an increasingly unpopular Apple development trend that is only excusable here because of the battery's longevity and the Kit's low price. Second, the Kit requires either a follow-on purchase of a pair of Nike+ shoes or an adaptation of your existing shoes. And third, as noted, the Kit is only compatible with the iPod nano, a limitation that appears to be without justification beyond easing Nike's manufacture of iPod-compatible clothes. Discussed further below, these issues take away only a little of the luster of an otherwise sparkling and astonishingly ambitious new iPod expansion - wireless, clothing, and sports, all at once.

Though the Sport Kit is easy to use, there's an incredible amount to cover given the changes it makes to the iPod nano and the iTunes software, as well as the new accessories and the Nikeplus.com web site it has spawned. Below, we run through all of these integrated components in turn; read through the sections that interest you, and skip those that don't.

For Apple and Nike's $29 asking price, the Nike + iPod Sport Kit includes one sensor and one receiver, which use a proprietary 2.4 GHz wireless technology to communicate wirelessly with each other. Each of the items is incredibly small: the sensor measures 1.37" by 0.95" by 0.3", and the receiver 1.03" by 0.62" by 0.22", collectively weighing .35 ounces. The box also includes a big instruction manual that walks users through accessory installation and the numerous new menu options Apple has added to the nano for Sport Kit users; the manual's abnormal-by-Apple-accessory-standards thickness is also attributable to multilingual instructions.

It's obvious that Apple and Nike want you to buy new shoes to use with the Sport Kit: old Nike shoes won't work, so the company has already released several pairs of brand new Nike+ shoes that are guaranteed to include Sport Kit sensor-sized compartments inside. The Air Zoom Moire ("mo-ray", $100) and Air Zoom Plus ($100) are widely available, and come in multiple colors including black, gray, and blue. Two Air Max shoes and a Shox Turbo III shoe will also be available for men and women, with an additional Shox Navina shoe only for women. If the Nike+ line is successful, additional models will follow. We bought four different pairs - men's and women's Moires and Air Zooms, shown here - and found them equal parts stylish, comfortable, and decently priced. You don't pay a higher than standard Nike premium for Nike+ shoes, which is great, and so long as you like the brand, there are enough styles to choose from that no one's fashion or comfort needs will go unmet.

If you don't like or can't afford new Nikes, you have options: the sensor can conceivably be put into any pair of shoes, achieving a near-identical effect to the Nike+ designs, but you'll have to modify one shoe to make the sensor work. One option is to cut a hole in the center of the left shoe's bottom interior foam padding, then stuff the sensor inside, and preferably cover it again with a thin layer of foam, such as the insole. It will work properly. But we wouldn't recommend doing this: it might be uncomfortable for your foot, and will obviously damage your existing shoes. Just for kicks, we tried to come up with the cheapest and least shoe-damaging improvised working alternative we could, and developed this: the Timberland+ sandal, which features a two-inch piece of packing tape inside to hold the sensor in place above one foot.

It worked without a problem during a quarter-mile walk - using the device's calibration system is a always good idea to make sure that your strides are being properly measured - and it was nearly as comfortable as using the Nike+ compartments. Of course, its long-term resilience was low, but you can always just apply another piece of tape, assuming you want to be cheap. If you're going to go this route, readers have recommended similar options, such as putting the sensor in a shoelace-mounted key carrier, a low-cost option that will last a lot longer. Since Apple and Nike don't officially support these other options, consider them to be at your own risk and expense - if your shoes or the sensor get damaged, that's par for the course. We use and prefer the Nike+ shoes.

Strictly speaking, you don't need anything else in order to use the Sport Kit - assuming you want to hold or pocket your nano, the shoes and Kit are enough. But if you want to mount your nano while in motion, Nike has developed an entire line of Nike+-branded shirts, jackets, and shorts with nano-ready pockets, and in some cases, special holes for headphone cord management. The pockets hold the nano and sometimes have a reservoir for the Sport Kit's receiver, as well. Many of the designs use Nike's moisture-wicking Dri-Fit technology, which keeps you cool and dry while running, and we really liked the way the majority of the new items look - at least, in the abstract. Pro Compression shirts (below) could and should give way to looser-fitting, fully nano-ready gear.

But like the new Nike+ Sport Armband (iLounge rating: C-), reviewed separately as the cheapest Nike+ nano-holding option, these nano-ready clothes have their ups and downs. A positive is that their cord management systems work well with official Apple headphones and similarly tiny-plugged ones: you pop the plug end through the holes and wear the cable mostly inside your shirt or shorts rather than outside. But bigger headphone plugs won't fit the holes. More importantly, like the Sport Armband, the clothes don't let you see the nano's screen at all - the men's jacket actually hides the nano inside your sleeve - so be prepared to shuffle-ize your iPod, and not see performance updates on its screen. This is mitigated somewhat, but not entirely, by the fact that the Sport Kit now provides voice feedback for some of its performance data. If you need screen access, Nike's previously released Nike Sport Armband for the nano (iLounge rating: B) provides partial viewability, and numerous other nano armbands we've reviewed and preferred do the same.

We have confirmed that the Sport Kit is, at least for the moment, incompatible with all iPods save the nano. Connecting it to the 5G iPod brings up a screen that says, "The currently attached accessory is not supported by this iPod," the same message that appears on a nano without version 1.2 (or later) system software. Earlier iPods do not visibly recognize that the device has been connected, and Apple has not announced plans to support future iPods, either.

Once you've purchased the nano, Sport Kit, and shoes, you need to make sure that the nano has been plugged into a computer and updated to version 1.2 of its iPod Software. You'll also need iTunes 6.0.5 or later. Once this is done, you're ready to connect the Sport Kit's sensor and receiver to your shoes and nano, respectively.

The sensor is inserted into a pair of shoes by removing a padded top inner insole to reveal a small hard plastic compartment underneath. This compartment is initially stuffed with an orange sensor-sized insert, which you remove and replace with the Sport Kit's similarly hard plastic part. Removing the sensor is easy, as the sides of the compartment and sensor are rounded, and pressing against the sensor's flat face will nudge it out of the slot. Then you just replace the pad, and put on the shoes.

Connecting the iPod nano to the receiver is even easier. The receiver's even smaller than the sensor, and goes right into the nano's bottom Dock Connector port. It leaves ample room for connection to any pair of headphones you prefer, and activates a new menu option on the nano's main menu: Nike+iPod. What follows when you select this option is one of the broadest arrays of new iPod menu options yet, a testament to what must have been an amazing amount of work by Apple and Nike on this technology.

The Nike+iPod menu lets you choose your preferred workout from 4 primary options: Basic ("just get me working out"), Time ("pick your preferred number of minutes, then go"), Distance ("choose a specific number in .05 mile increments or use common runners' settings"), and Calories ("set a custom number or go from 100-800 in 100-calorie increments"). But first, you'll want to go to the Workout Settings menu, which gets the Sport Kit set up for your personal use.

An option called PowerSong lets you pick one song that you can activate with a single button press at a point in your run when you need extra energy. You hold down the iPod's central Action button for a couple of seconds, and the song title appears in red on the screen. Spoken Feedback provides extremely impressive female or male voice feedback, which kicks in automatically during your run to provide pacing information, such as the fact that you're at the halfway point, have 100 meters left, or have finished the workout. It fades in gently on top of your music rather than interrupting, then fades out, which is both surprising and desirable; while imperfect in the sense that it sounds a little computer-synchronized, the voice cues are otherwise very well done, and manually activated by lightly pressing the Action button. You can also pick whether to use Miles or Kilometers for on-screen displays, and calibrate the Sport Kit to your personal body settings.

Strictly speaking, there's no need to use the Sport Kit's menus to help the sensor and receiver connect to each other: the nano will tell you to walk around if it needs you to re-establish a connection. However, you can pair a receiver with a different sensor, go through a calibration procedure (discussed below) to make the system more accurate, and tell the device how much you weigh in order to improve its sensitivity. It's worth your time to go through these steps - they do make the distance and calorie measurements more accurate.

Once you have everything set up as you prefer, you use your chosen workout track (Basic, Time, Distance, or Calories) to go for a run. The process is exceedingly simple, and the text - while not flashy - is easy to read on the iPod nano's screen.

You'll see the screen above - or something quite like it - while you're working out. In Basic or Time mode, your current time is indicated at the screen's bottom in red large digits, with the number of miles you've covered, your pace, and the current song's title on the screen above it in smaller text. In Distance mode, distance is in large numbers, with time, pace and song above, and in Calories mode, calories are the big number, with distance, time, and song above. While on this screen, you can still adjust iPod song volume, play/pause status, and track forwards or backwards.

When you've finished your workouts, the nano displays simple statistical data on what you've accomplished - the screen above shows a quick, poor run with a sled dog who wasn't much of a running companion in 90-degree heat. You can also see full details on prior performances.

The Sport Kit uses an accelerometer that tracks a user's running or walking motion with 90% precision out of the box, and around 97% precision once calibrated by the user. Combining that new piece of hardware with new software and your personal data (weight and pacing over 400-meter walks and runs), it can make "close-enough" calculations as to distance, pacing, and calorie burning accomplished during timed or open sessions. In our initial uncalibrated testing, which has been confirmed by reader reports, the Sport Kit was occasionally off by as much as the expected 10% on distance, but mostly within that margin; calibration produced more accurate results.

Our only issue with the calibration was a small one: because it is one of the only Nike+iPod features to lack voice feedback, it was a pain when attempted while inside Nike's Nike+ Sport Armband, which like other Nike+ nano pockets renders the screen unusable. You'll need to pick menu options and run a set distance to complete the calibration, but the Sport Kit won't tell you when you're done - entirely unlike running in any of its other modes. Adding voice feedback here, and better yet, a clear screen protector to Nike+ clothing, would make this process a lot easier to deal with.

On the other hand, pairing of the two devices was almost always quick and painless, accomplished with only a minimum of effort: the iPod tells you to walk around to activate the sensor, and within seconds, the workout is ready to start. Only once out of 30 or 40 times did we have an issue establishing a connection, and it was resolved by simply unplugging the receiver, then reattaching it. According to a new Apple FAQ on the Sport Kit, the sensor and receiver use "a proprietary low-power 2.4 GHz radio protocol" to communicate with one another, which the company points out "is not Bluetooth or Wi-Fi." A contact informed iLounge some weeks ago that the proprietary 2.4 GHz protocol was a limited, small stack variant of a more commonly known 802.11 wireless protocol. Despite the fact that they share the same 2.4 GHz radio spectrum, Apple's new FAQ notes that it has tested and engineered the Sport Kit to ensure that it will not interfere with existing wireless phone, cell phone, and Wi-Fi networks.

Notably, the Sport Kit's sensor contains a non-replaceable battery that has a lifespan of over 1,000 active hours, and will alert you when roughly 2 weeks of life remain. The good news is that you'd have to be a serious but slow runner or walker to use up the battery within two or three years of the Sport Kit's purchase. The bad news is that when the sensor's battery dies, it's not replaceable, so you'll need to buy a new Sport Kit. Few iPod accessories have a built-in expiration date, and given existing consumer complaints about this aspect of iPod hardware, Apple really shouldn't be going further down this road.

By contrast, Apple's receiver drains a small amount of power from the iPod nano, and should last indefinitely, though it will not be useful without a sensor. That said, you can re-pair it to a new sensor in the future if you have any need to do so, which will be great if Apple and Nike decide to sell extra sensors, or bundle them with future Nike+ shoes.

Once you've returned to your computer, connecting your iPod to its charging and synchronization cable will bring up a series of new iTunes screens - most likely. It actually took two synchronization attempts for iTunes to fully recognize the Sport Kit on the nano; during the first attempt, we noticed that a number of new directories had been quietly created by the iPod to store the workout data.

Inside the iPod_Control folder, in a sub-folder called Device, is a sub-sub-folder called "Trainer." Inside Trainer is another folder called Workouts, with a sub-folder called Empeds, and a sub-sub-folder with your serial number. Inside that final folder is a set of XML-format database files with your performance data, one file per workout. The data is viewable in text format, should you care to do so.

Most people won't care about those tiny files; iTunes handles all of their synchronization automatically. And quickly. Once you've used iTunes to establish an account with Nike, which is very similar to establishing an account with Apple, the data is transferred at lightning-fast speed to your computer, and then to the Nikeplus.com web site for viewing and comparisons. You're asked whether you want to visit Nikeplus.com, or just continue using iTunes.

It's hard to give Nike enough credit for the beauty and simplicity of the interface it's created for the Nike+ web site. The company has combined clean, attractive photography with easy-to-use buttons and great graphic design. Apple's upload of the data to the site takes place without any major user intervention, which is an added bonus. We only had one upload error during testing - other syncs worked fine - and it was resolved by an automatic re-upload as quickly as it was reported to us.

If you want to stop these uploads, you do so in a new Nike+iPod sub-tab of the iPod Tab in iTunes Preferences. Just uncheck "Automatically send workout data to nikeplus.com," and the transfer won't take place during synchronization. If you never want the data to be sent, don't sign up for a Nike account. It's your choice.

We'd recommend using the site. If Apple wasn't directly involved in developing the site, which we would guess it was, its iPod interface designers should take some notes: the web site looks leagues better than the iPod's text-only screens, and really enhances the experience of reviewing your data. It is as nicely done as we could imagine, and the designers deserve special praise: we can only hope that future iPods evolve in this visual direction.

Nikeplus.com shows all of your workouts in graphical form, letting you see your best and worst times in a flash. Rolling your mouse over any of them reveals specific statistics; a tracker at the top of the page tells you what your complete performance history is, and offers you quick access to your records and time scale comparison information.

The interface shows 12 days of runs as a default, changing to 12 weeks, 12 months, or "all runs" as you prefer.

In the near future, Nike's web site also will allow you to do comparisons between your performance and that of other named runners around the world. Under Community, the site lists the total number of miles Nike + iPod Sport Kit runners have run to date, with top tens for distance, duration, fastest 5K run, and fastest 10K run. The feature isn't fully operational yet, but this will make the Sport Kit even more of a cool toy than it already is.

Conclusions

What Apple and Nike have achieved with the Nike+iPod Sport Kit is a nearly unqualified triumph: an expansion of the iPod nano into a digital sport running and walking partner, using add-on technology that works well and is easy enough for anyone to use. While we won't go so far as to claim that it will replace the need for gyms or even just their treadmills, the Kit's cool features - voice feedback, big on-screen text focused on your workout goal, PowerSongs, and Nikeplus.com - are generally so well-done for the reasonable price that you can easily look past the system's few flaws. It helps tremendously that Nike has augmented the Sport Kit with so many good shoe options, with more on the way; we hope that its other apparel options will improve as time goes on, but if they don't, we have plenty of other options.

Our only real concerns are those noted above: the accessory's battery-induced death, its incompatibility with unmodified non-Nike+ shoes, and its failure to work with iPods other than the nano. Of these, we consider the last issue to be the most serious because it is the least surmountable, and an unpleasant way to reward people who shelled out $300 or more for full-sized iPods. The Sport Kit is a good value for any current iPod owner at $29 plus the cost of a pair of shoes; at that price plus the cost of a nano, it's easier to pass up.

Despite those small blemishes, we're very impressed by what Apple and Nike have accomplished with the Nike+iPod Sport Kit - this is an amazingly well-assembled, turnkey personal exercise tracking solution, at least for runners and walkers, and highly recommended to iLounge readers. Our hope is that both companies follow up this Sport Kit with additional options for other types of athletes, as this has opened our eyes to just how much potential our favorite media player really has when properly accessorized.

[Editor's Note: In late 2008, Apple released the second-generation iPod touch, the company's first device with an integrated Nike+ receiver, eliminating the need for a Dock Connector attachment. This was followed by the June 2009 release of the iPhone 3GS, the first iPhone with integrated Nike+ receiver capability. Both of these devices can pair with a "Nike + iPod Sensor," a $19 accessory that is nothing more than the plastic wireless sensor component from the Sport Kit; these Sensors are also sold as replacements for the battery-limited Sport Kit part. The post-2006 Nike + iPod developments for touchscreen iPods, including the user interface, are highlighted in this article.]

Editors' Note: iLounge only reviews products in "final" form, but many companies now change their offerings - sometimes several times - after our reviews have been published.
This iLounge article provides more information on this practice, known as revving.